It is the long range purpose of this project to determine whether mutational processes are involved in in vitro malignant transformation of mammalian cells by diverse chemical and physical carcinogens. Research efforts during the past year have centered on (1) determination of cell culture conditions necessary to maintain morphological differences between transformed and normal cells, (2) standardization of the survival responses of Chinese hamster V79 cells to chemical carcinogens, caffeine, and UV light, and (3) study of assay conditions necessary for quantitative measurements of induced mutation frequencies in cultured X. pigmentosum human cells. Future efforts will be directed toward simultaneous mutagenesis and transformation assays utilizing both human and Syrian hamster embryo cells in culture.